Every gathering has a stretch at the beginning where nothing quite works.
People are still arriving. Half the room is standing. Somebody is looking for a plug point. The host is at the door rather than seated. Whoever came first is stranded in a corner wondering whether they were too early, because they were.
From where we sit, this is the most predictable fifteen minutes of any evening, and the most misread. Hosts tend to panic slightly. They fill the silence, apologise for the delay, urge people to sit before people are ready to sit. Occasionally they ask us to start, hoping music will fix it.
It does not, particularly. A set that begins into a half-formed room has to be rescued later.
What actually happens, if you leave it alone, is that the room assembles itself. Somewhere around the twelve-minute mark a critical mass of people are seated, the standing conversations drop by half, and the noise in the room changes pitch. It becomes lower and rounder. Anyone who has played a lot of these evenings learns to listen for that shift rather than watch the clock.
That is the moment to begin. Not before.
The practical consequence is that your invitation time and your music time should be two different things, and you should plan for them to be about half an hour apart. If you want singing at seven, ask people for half six and mean it. Tell the musicians seven, and tell them it will probably be ten past.
The other consequence is subtler. Those fifteen minutes are not dead time to be minimised. They are when people greet each other, find where they want to sit, and decide what sort of evening this is going to be. A room that has done that properly sings within two bhajans. A room hurried past it stays polite for an hour.
So the advice, such as it is: put the diyas out, keep the light low from the start, have something to drink available, and then let people arrive at their own pace. Resist the urge to organise them.
The evening starts when the room goes quiet on its own. Your job is to notice.